At 8-10% O2, which physiologic effect occurs?

At 8-10% O2, which physiologic effect occurs?

• A. Dizziness
• B. Headache
• C. Nausea
• D. Unconsciousness with ashen face and blue lips

Answer: (D)

When ambient oxygen is extremely low, the brain quickly becomes severely hypoxic. The brain is highly sensitive to oxygen shortages, so loss of consciousness occurs as a rapid and critical sign. As oxygen delivery remains inadequate, the blood becomes highly deoxygenated, giving the skin a pale, ashen look and the lips a blue tint (cyanosis). So at 8-10% O2, unconsciousness with an ashen face and blue lips is the most immediate, defining physiologic effect. Early symptoms like dizziness or headache happen with milder hypoxia, and nausea can occur as well, but they are not the decisive outcome at such a profoundly low oxygen level.

When ambient oxygen is extremely low, the brain quickly becomes severely hypoxic. The brain is highly sensitive to oxygen shortages, so loss of consciousness occurs as a rapid and critical sign. As oxygen delivery remains inadequate, the blood becomes highly deoxygenated, giving the skin a pale, ashen look and the lips a blue tint (cyanosis). So at 8-10% O2, unconsciousness with an ashen face and blue lips is the most immediate, defining physiologic effect.

Early symptoms like dizziness or headache happen with milder hypoxia, and nausea can occur as well, but they are not the decisive outcome at such a profoundly low oxygen level.